1. Field of the Invention
The invention relates to a power management method and, more particularly, to a power management method of a computer system.
2. Description of the Related Art
Power management is an important function of a desktop computer and a portable peripheral device (such as a notebook), which needs a battery to provide power. At present, most of the computer systems support advanced configuration and power interface (ACPI) standard to manage the power. In the ACPI, an operating system, instead of a basic input output system (BIOS), generates a command to manage the power according to the interaction between the user and the operating system. Thus, the efficiency of the power source management is increased. The ACPI distributes the power to the system components effectively. Cooperating with hardware detecting information such as the temperature of a mother board, the speed of a fan, the voltage of a power supply, a proper voltage and a host operating frequency are provided to save power and improve the efficiency.
Under the management of the ACPI, the computer system can operate under different power states such as S0, S1, S2, S3 (suspend to RAM), S4 (hibernate, suspend to disk), S5 (soft off) according to different requirements. For example, under the S0 state, all of the hardware and the peripheral devices operate. Under the S1 state, the central processor unit (CPU) stops operations to reduce the power consumption of the CPU. Under the S2 state, the CPU is turned off. Under the S3 state, only the memory device has power to save power and prevent the operating system state stored in the memory from losing when power off. When back to the S0 state, the operating system can restore the operating system state quickly by accessing the memory device. Under the S4 state, the operating system state stored in the memory device under the S3 state is stored to a hard disk, and then the operating system is turned off. Under the S5 state, the computer system is turned off without storing the operating system state.
Furthermore, under the S0 state, when the system is idle, the user can set whether the main monitor is turned off automatically in settings of the system power management configuration. For example, the turn-off time of the main monitor can be set to be “one minute”, “none” and so on. Since it saves the power when the main monitor is turned off, some users would not select “none”, and they may set the main monitor to be power off after the system is idle for a certain time.